LESSON SUMMARY FOR: DATE STARTED: DATE COMPLETED: TIME: 60 minutes. TEACHING and LEARNING ACTIVITIES

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1 GRADE 10 SUBJECT Physical Sciences WEEK 34 Lesson 1 TOPIC Gravitational Potential Energy LESSON SUMMARY FOR: DATE STARTED: DATE COMPLETED: TIME: 60 minutes LESSON OBJECTIVES At the end of the lesson learners should be able to: Define gravitational potential energy Determine gravitational potential energy of an object TEACHING and LEARNING ACTIVITIES 1. TEACHING METHOD/S USED IN THIS LESSON: Demonstration ; observation, question and answer method 2. LESSON DEVELOPMENT 2.1 Introduction a) PRE-KNOWLEDGE learners need understanding of the following: (i) Different forms of energy (ii) Potential energy of an object b) BASELINE ASSESSMENT (educator to design a worksheet/ transparency or write questions on the board [preferably a worksheet to save time] to gauge the learners memory of their relevant prior knowledge) QUESTIONS for the BASELINE ASSESSMENT i) List five forms of energy ii) iii) Define potential energy Give three examples of potential energy [5 min] iv) What are the factors that affect the gravitational potential energy of an object Page 1

2 c) Do corrections i) Sound, light, heat, chemical energy, kinetic energy, potential energy etc. ii) Potential energy is the energy due to object s position or state.(stored energy) iii) Electrical potential energy, gravitational potential energy and Chemical potential energy iv) Mass and the height of an object 2.2 Main Body (Lesson presentation) [30 min] Gravitational potential energy is the energy an object ha due to its position in a gravitational field relative to some reference point. Gravitational potential energy (Ep) is a scalar quantity and is measured in Joules (J). * Some books use the symbol PE or U for gravitational potential energy where = gravitational potential energy (measured in joules, J), m = mass of the object (measured in kg) g = gravitational acceleration (9,8 m s 2 ) h = perpendicular height from the reference point (measured in m) Reference point is the zero energy level. Example of this reference point is the ground. Gravitational potential energy (EP) of an object is directly proportional to the mass of an object. EP α m; and Gravitational potential energy (EP) of an object is directly proportional to the height of an object EP α h Page 2

3 As the money back moves upwards: Kinetic energy decreases and gravitational potential energy increases Kinetic energy decreases is converted into gravitational potential energy increases As the money back moves downwards: Kinetic energy increases and gravitational potential energy decreases Kinetic energy decreases is converted into gravitational potential energy increases Example Solution A brick with a mass of 2kg is lifted to the top of a 5 m high roof. It slips off the roof and falls to the ground. Calculate the gravitational potential energy of the brick a) at the top of the roof b) on the ground once it has fallen. a)ep = mgh = 2(9,8)5 = 98 J b) On the ground, the height is zero. Therefore gravitational potential energy is zero Learners activities 10 min (Consider g = 9.8 m s -2 near the surface of the Earth.) 1) Climbing a vertical rope is difficult. You have to lift your full body weight with your arms. If your mass is 60 kg and you climb 2.0 m, by how much do you increase your gravitational potential energy? 2) A block of bricks is raised vertically to a bricklayer at the top of a wall using a pulley system. If the block of bricks has a mass of 24 kg, what is its weight when it is raised 3,0 m? Calculate its increase in gravitational potential energy when it reaches the top of the wall. Page 3

4 3) Travelling in a mountainous area, a bus of mass 3 tonnes reaches the edge of a steep valley. There is a 1 km vertical drop to reach the valley below, but 20 km of road to get there. What gravitational potential energy will the bus lose in descending to the valley bottom? 4) Assuming the bus in question 3 does not change its cruising speed on the way down, where does the gravitational potential energy go? Why is there a risk of brake failure in this situation? 5) A basketball player, who is 2m tall, holds a 500g netball 0,3 m above his head and shoots for the goal net which is 3 m above the ground. Assume that his feet do not leave the ground as he shoots for a goal and answer the following questions: What is the gravitational potential energy of the ball: 5.1. when it lands on the ground after the goal is scored? 5.2. when he is about to shoot it into the net? 5.3. when it gets right into the net? Corrections [7 min] 1 E p = mgh = 60 x 9.8 x 2 = 1176 J 2 Weight = mg = 24 x 9.8 = 235. N Page 4

5 Change in EP = mgh = 24 x 9.8 x 3.0 = J 3 Change in EP = mgh = 3000 x 9.8 x 1000 = 2.94 x 10 7 J 4 Since the bus gains no kinetic energy (its speed stays the same) it must be using its brakes, and all the gravitational potential energy lost by the bus in converted to heat in the brakes. There is a risk of brake failure if the brakes overheat. 5.1 When the ball lands on the ground after the goal is scored, the height of the ball is 0 m. And the gravitational potential energy is zero (0) J 5.2 The height from which the ball is shot h =( 2 + 0,3)m = 2,3 m, but the mass must be converted to kg. m = 500/1000 = 0,5 kg EP= mgh = (0,5)(9,8)(2,3) = 11,27 J 5.3 EP= mgh = (0,5)(9,8)(2,3) = 14,7 J 3. Conclusion Activity to Reinforce lesson(educator may summarise the main aspects of the lesson).[5 min.] HOMEWORK QUESTIONS/ ACTIVITY (educator must give learners a few questions to answer at home by either writing them on the chalkboard or giving an exercise from the prescribed textbook) [30 min] Page 5

6 RESOURCES USED: worksheets, textbooks Reflection/notes Name of Teacher: Sign: Date: HOD: Sign: Date: Page 6

7 GRADE 10 SUBJECT Physical Sciences WEEK 34 Lesson 2 TOPIC Kinetic energy LESSON SUMMARY FOR: DATE STARTED: DATE COMPLETED: TIME: 60 minutes LESSON OBJECTIVES At the end of the lesson learners should be able to: Define kinetic energy Determine kinetic of an object TEACHING and LEARNING ACTIVITIES 1. TEACHING METHOD/S USED IN THIS LESSON: Demonstration ; observation, question and answer method 2. LESSON DEVELOPMENT 2.1 Introduction a) PRE-KNOWLEDGE learners need understanding of the following: (i) Change in forms of energy (ii) Kinetic energy of an object b) BASELINE ASSESSMENT (educator to design a worksheet/ transparency or write questions on the board [preferably a worksheet to save time] to gauge the learners memory of their relevant prior knowledge) QUESTIONS for the BASELINE ASSESSMENT [5 min] i) To which form of energy does gravitational potential energy of a falling object change? ii) c) Do corrections i) Kinetic energy Define kinetic energy. iii) What are the factors that affect the kinetic energy of an object? ii) Kinetic energy is the energy an object will possess as a result of its motion iii) Mass and velocity of an object Page 1

8 2.2 Main Body (Lesson presentation) [30 min] Kinetic energy is the energy an object has because of its motion. This means that any moving object has kinetic energy. Kinetic energy is defined as: where is the kinetic energy (measured in joules, J) m = mass of the object (measured in kg) v = velocity of the object (measured in m s 1 ). Sometimes kinetic energy is represented by the symbol KE Therefore the kinetic energy depends on the mass and velocity of an object. The faster it moves, and the more massive it is, the more kinetic energy it has. Where the mass is not in kg and the velocity not in m s -1, mass and/or velocity must be converted to SI units The diagram below shows a Formula 1 racing car that started racing at point A. At A, the car is at rest and the is zero. As it passes B the velocity of the car is v and the kinetic energy A B Example A motorcycle with a mass of 250 kg and a car with a mass of 1250 kg are standing parallel waiting for the traffic lights to turn green. As they pass the traffic officer seated with his speed camera alongside the straight road, the traffic officer observed a speed of 160 km h -1 for the motorcycle and 120 km h -1 or the car. Calculate the kinetic energies of both the car and the motorcycle as they each pass the traffic officer. Solutions To convert km h -1 to m s 1, simply divide by 3,6 0r multiply velocity by 1000 and divide by 3 600(60x60) i.e. an hour For the motorcycle For the motor car Page 2

9 = ½ (250)(44,44) 2 = ½ (1250)(33,33) 2 = ,20 J = ,56 J = 2,47x 10 5 J = 6,94 x10 5 J teach scientific notation here Learners activities 10 min A 1 kg brick freely falls off a 4 m high roof. It reaches the ground with a velocity of 8,85 m s 1. What is the kinetic energy of the brick a) when it starts to fall? b) when it reaches the ground? Describe the relationship between an object's kinetic energy and its: a) mass and b) velocity A stone with a mass of 100 g is thrown up into the air. It has an initial velocity of 3 m s 1. Calculate its kinetic energy: a) as it leaves the thrower's hand. b) when it reaches its turning point A shot putter heaves a 7,26kg shot with a final velocity of 7,5 m s 1. What is the kinetic energy of the shot? An object is slowing down to a final speed three times smaller than its initial speed. What is the ratio of the final and initial kinetic energies? Corrections a) Zero J, v = m s a) The kinetic energy is directly proportional to the mass. As the mass increases, so does the kinetic energy. E k α m b) The kinetic energy is directly proportional to the square of the velocity, i.e. E k α v 2 Page 3

10 b) At the turning point the velocity of the stone is 0 m s 1. So the kinetic energy is: E K = ½mv (a) Ek =½mv 2 = ½(0,1)(0) 2 = 0 J = ½(0,1)(3) 2 = 0,45 J EK = ½ mv 2 = ½ (7,26)(7,5) 2 = 204, 19 J Ratio of the E2 : Ratio of the E1 if the final velocity is 3 1 and the initial velocity is v ½ m( 3 1 v) 2 = ½ mv 2 ( 9 1 )( ½ mv2 ) = ½ mv 2 therefore the ratio is Page 4

11 1 : Conclusion Activity to Reinforce lesson(educator may summarise the main aspects of the lesson).[5 min.] HOMEWORK QUESTIONS/ ACTIVITY (educator must give learners a few questions to answer at home by either writing them on the chalkboard or giving an exercise from the prescribed textbook) [30 min] RESOURCES USED: worksheets, textbooks Reflection/notes Name of Teacher: Sign: Date: HOD: Sign: Date: Page 5

12 GRADE 10 SUBJECT Physical Sciences WEEK 34 Lesson 3 TOPIC EP and EK Calculations(mixed exercises) LESSON SUMMARY FOR: DATE STARTED: DATE COMPLETED: TIME: 60 minutes LESSON OBJECTIVES At the end of the lesson learners should be able to: Calculate gravitational potential energy Calculate kinetic energy TEACHING and LEARNING ACTIVITIES 1. TEACHING METHOD/S USED IN THIS LESSON: Induction method, question and answer method 2. LESSON DEVELOPMENT 2.1 Introduction a) PRE-KNOWLEDGE learners need understanding of the following: (i) Fundamental forms of energy (ii) Equations to calculate kinetic energy and gravitational potential energy (iii) Factors on which kinetic energy and gravitational potential energy depend b) BASELINE ASSESSMENT (educator to design a worksheet/ transparency or write questions on the board [preferably a worksheet to save time] to gauge the learners memory of their relevant prior knowledge) QUESTIONS for the BASELINE ASSESSMENT [5 min] i) Explain what happens to the gravitational potential energy of an object freely falling from a height h. ii) iii) If an object is thrown vertically upwards to a certain height, there are changes in kinetic and potential energy as the object moves towards the maximum height. What changes in kinetic and gravitational potential energy does an object experience on its way up? Define a closed system Page 1

13 c) Do corrections i) Gravitational Potential energy is converted into kinetic energy (No air friction) ii) Kinetic energy of an object is converted into gravitational potential energy. EK decreases and EP increases iii) A closed system is the system where there are no external forces(non-conservative forces) acting on the object 2.2 Main Body (Lesson presentation) [30 min] Grade 10 Physical Science Lesson Plans Since this section is mainly about calculations, provide learners with a short summary and supervise them throughout the exercise. Even learners not asking questions or your attention should be checked, so that struggling learners can be identified. Gravitational Potential energy is the energy an object has due to its position EP = mgh Gravitational potential energy is maximum at the highest point and it is minimum at the point of reference Kinetic energy is the energy an object will possess as a result of its motion EK = ½ mv 2 Kinetic energy is maximum where the velocity is maximum and lowest were the velocity is minimum Learners activities 10 min What is the final velocity of a kg truck, if J of energy is used to accelerate it? A bike rider approaches a hill with a speed if 8.5m/s. The total mass of the rider and the bike is 85kg. (a) Find the kinetic energy of the bike and rider at the bottom of the hill. (b) The rider coasts up the hill. Assuming there is no friction, at what height will the bike and rider have all kinetic energy converted to gravitational potential energy (come to a stop)? A 98N sack of grain is hoisted to a storage room 50m above the ground floor of a grain elevator. (a) What is the potential energy of the sack of grain at height of 50 m? (b) The rope being used to lift the sack of grain breaks just as the sack reaches the storage room. The kinetic energy of the sack just before it strikes the ground floor is J. What is the speed of the sack just before it hits the ground? Page 2

14 2.2.4 How fast must a kg bullet travel if it is to have the same kinetic energy as a 20,000 kg locomotive traveling at 2 m s -1? A roller coaster car of mass 465 kg rolls up a hill with a vertical height of 75 m from the ground. What is the change in potential energy relative to the ground? (a) E K = ½ mv 2 Corrections EK = ½ mv = ½ (5 700)v 2 = ½ (85)(8,5) 2 = 3 070,63 J b) If all kinetic energy is converted, E P = 3 070, 63 J 3070,63 = (85)(9,8)h h = 3, 69 m v = 27,78 m s -1 b) E K = ½ mv 2 mg = 98 N (a) EP = mgh Fg = mg = 98 N = ½ (10)v 2 m(9,8) = 98 = 98 x 50 v = 31, 30 m s -1 m = 10 kg = J 2.4 EK(bullet) = EK(locomotive) ½ m1v 2 (bullet) = ½ m2v 2 (locomotive) (0,,0050)v 2 = (20 000) E P = E P(top) - E P(ground) = (465)(9,8)(75) - (465)(9,8)(0) = J v = m s -1 Page 3

15 3. Conclusion Activity to Reinforce lesson(educator may summarise the main aspects of the lesson).[5 min.] HOMEWORK QUESTIONS/ ACTIVITY (educator must give learners a few questions to answer at home by either writing them on the chalkboard or giving an exercise from the prescribed textbook) [30 min] RESOURCES USED: worksheets, textbooks Reflection/notes Name of Teacher: Sign: Date: HOD: Sign: Date: Page 4

16 GRADE 10 SUBJECT Physical Sciences WEEK 34 Lesson 4&5 TOPIC Mechanical energy LESSON SUMMARY FOR: DATE STARTED: DATE COMPLETED: TIME: 60 minutes LESSON OBJECTIVES At the end of the lesson learners should be able to: Define mechanical energy Determine mechanical energy of an object using the equation EM = EK + EP TEACHING and LEARNING ACTIVITIES 1. TEACHING METHOD/S USED IN THIS LESSON: Induction method, question and answer method 2. LESSON DEVELOPMENT 2.1 Introduction a) PRE-KNOWLEDGE learners need understanding of the following: (i) Gravitational potential energy and kinetic energy (ii) Sum of gravitational potential energy and kinetic energy at a point b) BASELINE ASSESSMENT (educator to design a worksheet/ transparency or write questions on the board [preferably a worksheet to save time] to gauge the learners memory of their relevant prior knowledge) QUESTIONS for the BASELINE ASSESSMENT [5 min] i) Define gravitational potential energy and kinetic energy ii) What is the sum of kinetic energy and gravitational potential energy called? iii) iv) How much is the kinetic energy of an object thrown vertically upwards at its turning point? Explain. What is the relationship between kinetic energy at the turning point and the gravitational potential energy at the reference point(zero energy level)? Page 1

17 c) Do corrections i) Gravitational potential energy is the energy an object has due to its position within a gravitational field relative to another object and Kinetic energy is the energy an object will possess as a result of its motion ii) Mechanical energy iii) Zero J. The velocity of an object thrown vertically upwards is 0 m s -1 at the turning point. Kinetic energy is dependent on the velocity iv) Kinetic energy at the turning point is equal gravitational potential energy at the zero energy level (point of reference) 2.2 Main Body (Lesson presentation) [30 min] Mechanical energy (EM )is the sum of the gravitational potential energy and the kinetic energy of a system. Mechanical energy is mathematically written as: (1) that can be expanded and written as (2) The symbols E and ME are sometimes used to denote mechanical energy, but for this lesson EM will be used. Mechanical energy is measured in Joules(J), the same unit as gravitational potential energy and kinetic energy. NB. It is scientifically wrong to mix symbols in an equation. e.g EM = PE + K. Though each symbol represents the correct energy, the symbols were used inappropriately. Example 1 Calculate the total mechanical energy for a ball of mass 0,15 kg which has a kinetic energy of 20 J and is 2 m above the ground. Page 2

18 Learners activities 10 min Frank, a San Francisco hot dog vendor, has fallen asleep on the job. When an earthquake strikes, his 3,00 X 10 2 kg hot dog cart rolls down Nob Hill and reaches point A, 3 m above the ground at a speed of 8,00 m s -1. Calculate the mechanical energy of the cart at A A stone with a mass of 50 g is thrown vertically upwards into the air. At a height of 8 m above the position it was thrown, the stone has a velocity of 6 m s - 1. Determine the mechanical energy of the stone at a height of 8 m A golf ball with a mass 2 kg is released from point A and freely falls from a height of six metres above the ground A If it passes point B which is 2 of the total height at a speed of 3 m s -1. Calculate its mechanical energy at point B B 3 C An apple of mass 20 g falls from a tree 5 m high. At a height of 3 m above the ground the velocity of an apple was observed to be 5 m s -1 and at a height of 1 m it was observed to be 8 m s -1. Calculate the mechanical energy of an apple at the height of 5 m, 3 m and 1 m Corrections Mechanical energy at A = mgh + ½ mv 2 = (3,00x10 2 )(9,8)(3) + ½ (3,00x10 2 )(8,00) 2 Page 3

19 = J At point B height is = 2 x 6 = 4 m Convert the mass of the stone first. = 0.05kg 1000 = (2)(9,8)(4) + ½ (2)(3) 2 = (0,05)(9,8)(8) + ½ (0,05)(6) 2 = 87,40 J = 4,82 J m = 0,02 kg At height of 5 m At height of 3m At height of 1 m = (0,02)(9,8)(5)+1/2 (0,02)(0) 2 = (0,02)(9,8)(3)+1/2 (0,02)(5) 2 =(0,02)(9,8)(1)+1/2 (0,02)(8) 2 = 0,98 J = 0,838 J = 0,836 J Page 4

20 3. Conclusion Activity to Reinforce lesson(educator may summarise the main aspects of the lesson).[5 min.] HOMEWORK QUESTIONS/ ACTIVITY (educator must give learners a few questions to answer at home by either writing them on the chalkboard or giving an exercise from the prescribed textbook) [30 min] RESOURCES USED: worksheets, textbooks Reflection/notes Name of Teacher: Sign: Date: HOD: Sign: Date: Page 5

21 GRADE 10 SUBJECT Physical Sciences WEEK 35 Lesson 1 TOPIC Conservation of Mechanical Energy LESSON SUMMARY FOR: DATE STARTED: DATE COMPLETED: TIME: 60 minutes LESSON OBJECTIVES At the end of the lesson learners should be able to: State law of conservation of mechanical energy Describe the condition(s) of factors that determine whether the system is an isolated(closed system ) or not Describe a closed system Explain the effects of friction (no-conservative forces) on mechanical energy TEACHING and LEARNING ACTIVITIES 1. TEACHING METHOD/S USED IN THIS LESSON: Induction method, question and answer method 2. LESSON DEVELOPMENT 2.1 Introduction a) PRE-KNOWLEDGE learners need understanding of the following: (i) Gravitational potential energy and kinetic energy (ii) Sum of gravitational potential energy and kinetic energy b) BASELINE ASSESSMENT (educator to design a worksheet/ transparency or write questions on the board [preferably a worksheet to save time] to gauge the learners memory of their relevant prior knowledge) QUESTIONS for the BASELINE ASSESSMENT i) Define an closed system ii) iii) iv) Define mechanical energy [5 min] How much is the kinetic energy of an object thrown vertically upwards at its turning point? Explain. What is the relationship between kinetic energy at the turning point and the gravitational potential energy at the reference point(zero energy Page 1

22 c) Do corrections i) A closed system is a system where there are no external forces acting on the object. (No friction, air resistance or any other external forces) ii) Mechanical energy is the sum of object s gravitational potential energy and kinetic energy iii) Zero J. The velocity of an object at the turning point is 0 m s -1. Kinetic energy is dependent on the velocity iv) Kinetic energy at the turning point is equal gravitational potential energy 2.2 Main Body (Lesson presentation) [30 min] Mechanical energy is the sum of the gravitational potential energy and the kinetic energy of a system. In a closed system,the sum of kinetic energy and the potential energy remains constant at any point.mathematically it can be written as: Ek1 + Ep1 = Ek2 + Ep2. The Law of Conservation of Energy: Energy cannot be created or destroyed, but is merely changed from one form into another. Law of Conservation of Mechanical Energy: The total amount of mechanical energy, in a closed system in the absence of dissipative forces (e.g. friction, air resistance), remains constant Since the mechanical energy remains constant, the sum of gravitational potential energy and the kinetic energy at any stage in a closed system must be equal. Otherwise the system is an open system. And in an open system some energy is converted into other forms of energy like sound, heat etc. Learners activities 10 min A 1 kg brick falls off a 4 m high roof. It reaches the ground with a velocity of 4,425 m s 1. Page 2

23 a) Calculate its mechanical energy on the : (i) roof (ii) ground b) Is mechanical energy conserved? Explain your answer Describe the relationship between an object's kinetic energy and its: a) mass b) velocity A stone with a mass of 100 g is thrown up 5m above the thrower s hand. It has an initial velocity of 4,95 m s 1. Calculate its kinetic energy: a) as it leaves the thrower's hand and its mechanical energy at that point. b) and mechanical energy when it reaches its turning point Tarzan, mass 85kg, swings down from a tree limb on the end of a 20m vine. His feet touch the ground 4.0m below the limb. How fast is Tarzan moving when he reaches the ground if it is a closed system? Page 3

24 Corrections ii ) E M(ground) = (E k2 + E p2) ground a (i) EM(roof) = (Ek1 + Ep1 ) roof = ( ½ mv mgh 2) = ( ½ mv1 2 + mgh1) = ( ½ x1x4,425 2 ) + (1x9,8x0) = ( ½ x1x0 2 ) + (1x9,8x4) = 9,79 J = 39,2 J (b) No, mechanical energy on the roof is not the equal to mechanical energy on the ground. Therefore some energy has done work against friction. Therefore this is not a closed system ( a) The kinetic energy is directly proportional to the mass. As the mass increases, so does the kinetic energy. Ek α m ( b) The kinetic energy is directly proportional to the square of the velocity, i.e. Ek α v (a) EK = ½ mv 2 leaving the thrower s hand (b) E K = ½ mv 2 at turning point = ½ x 0,1x 4,95 2 = 1.23 J = ½ x 0,1x 0 2 = 0 J EM(leaving hand) = (Ek1 + Ep1 ) leaving hand E M(turning point) = (E k2 + E p2 ) turning point = ( ½ mv1 2 + mgh1) Page 4

25 = ½ x 0,1x4, ,1x9,8x0 = 1,23 J = ( ½ mv mgh 2) ( Ek1 + Ep1)tree limb = (Ek2 + Ep2 ) ground = ½ x0,1x ,1 x 9,8 x 5 ( ½ x 85 x 0 2 ) + (85 x 9,8 x 4,0) = ( ½ x 85 x v 2 ) + ( 85 x 9,8 x 0) = 4,9 J J = 42,5 v v 2 = 78,4 v = 8,85 m s Conclusion Activity to Reinforce lesson(educator may summarise the main aspects of the lesson).[5 min.] HOMEWORK QUESTIONS/ ACTIVITY (educator must give learners a few questions to answer at home by either writing them on the chalkboard or giving an exercise from the prescribed textbook) [30 min] RESOURCES USED: worksheets, textbooks Name of Teacher: Sign: Date: HOD: Sign: Date: Page 5

26 GRADE 10 SUBJECT Physical Sciences WEEK 35 lesson 2 TOPIC Principle of conservation of Mechanical energy LESSON SUMMARY FOR: DATE STARTED: DATE COMPLETED: TIME: 60 minutes LESSON OBJECTIVES At the end of the lesson learners should be able to: Calculate the mechanical energy from the equation : EK1 + EP1 = EK2 + EP2 TEACHING and LEARNING ACTIVITIES 1. TEACHING METHOD/S USED IN THIS LESSON: Induction method, question and answer method 2. LESSON DEVELOPMENT 2.1 Introduction a) PRE-KNOWLEDGE learners need understanding of the following: (i) Gravitational potential energy and kinetic energy (ii) Sum of gravitational potential energy and kinetic energy iii) Change on mechanical energy brought by the external forces b) BASELINE ASSESSMENT (educator to design a worksheet/ transparency or write questions on the board [preferably a worksheet to save time] to gauge the learners memory of their relevant prior knowledge) [5 min] QUESTIONS for the BASELINE ASSESSMENT i) State the law of conservation of energy ii) What is the sum of kinetic energy and gravitational potential energy called? iii) How much is the kinetic energy of an object thrown vertically upwards at its turning point? Explain. iv) What is the relationship between kinetic energy at the turning point and the gravitational potential energy at the reference point(zero energy) Page 1

27 c) Do corrections i) Energy can neither be created nor destroyed but can change from one form to another. ii) Mechanical energy iii) Zero J. The velocity of an object at the turning point is 0 m s -1. Kinetic energy is dependent on the velocity iv) Kinetic energy at the turning point is equal gravitational potential energy at the zero energy level 2.2 Main Body (Lesson presentation) [30 min] The Law of Conservation of Energy: Energy cannot be created or destroyed, but is merely changed from one form into another. Law of Conservation of Mechanical Energy: The total amount of mechanical energy, in a closed system in the absence of dissipative forces (e.g. friction, air resistance), remains constant. This means that potential energy can become kinetic energy, or vice versa, but energy cannot disappear. For example, in the absence of air resistance, the mechanical energy of an object moving through the air in the Earth's gravitational field, remains constant (is conserved) Mechanical energy is conserved (in the absence of friction). Therefore we can say that the sum of the EK and the EP anywhere during the motion is the same. Examples and exercises below will try to explain conservation of mechanical energy of a pendulum, vertical motion and the motion on an incline We can now apply this to the example of the suitcase on the cupboard. Consider the mechanical energy of the suitcase at the top and at the bottom. We can say: Page 2

28 EK1 + EP1 = EK2 + EP2 If the pendulum bob is released from point A and it is a closed system: The pendulum will increase its velocity until it reaches maximum velocity at B and then starts to slow down again and reach velocity of zero at D, then swing back to point A. If there is no air resistance, the motion will forever continue. At A and D all E K is converted into E P, and at point B all E P is converted to E K Pendulum will have maximum gravitational potential energy at A and D and maximum kinetic energy at B. At point C, hallway between D and B, the kinetic energy is equal to gravitational potential energy Learners activities 10 min Page 3

29 1. A marble has a mass of 250 g. It is dropped from the top of an office building, a height of 200 m. The marble strikes the pavement below at a speed of 42.0 m/s. How much of the marble's gravitational potential energy was not converted into kinetic energy as it fell? 2. A pendulum of mass 4 kg is dropped from the position shown in the diagram (0.50 m above the equilibrium position). What is the speed of the pendulum bob as it passes through the equilibrium position? 3. A heavy box slides down a frictionless incline 12.0 m long that makes an angle 25,0 0 with the horizontal, as shown in the diagram. If the box starts from rest at the top of the incline, what is the speed at the bottom of an incline? (Hint: find the height and take out a common factor of m on both sides). i.e. this problem is solved without being given the mass. 4. A roller-coaster car starts from rest at point A. What is the speed of the car at points B and C if the track is frictionless? Page 4

30 Corrections 1. Ep( top) = mgh = ( 0,25 x 9,8 x 200) = 490 J E K (bottom) = ½ mv 2 = 0,5 x 0,25 x 42 2 = 220,5 J Gravitational potential energy not converted into kinetic energy = ,5 2 (Ek1 + Ep1)top = (Ek2 + Ep2) bottom = 269,5 J ( ½ x 4 x 0 2 ) + (4 x 9,8 x 0,5) = ( ½ x 4 x v 2 ) + (4 x 9,8 x 0) ,6 = 2 v v = 3,13 m s -1 sin 25 0 = h 12,0 h = 12,0 sin 25 0 h = 5,07m 3. (Ek1 + Ep1) top = (Ek2 + Ep2) bottom ½ mv1 2 + mgh1 = ½ mv2 2 + mgh2 m ( ½ v1 2 + gh1) = m ( ½ v2 2 + gh2) ½ x ,8 x 5,07 = ½ v ,8 x 0 Page 5

31 99,372 = v2 2 vbottom = 9,97 m s -1 4 Mechanical energy at A = (Ek2 + Ep2) top v = 0 at A. The car starts rom rest = x 9,8 x 20 E M (at A) = E M (at B) = J = (500x 8 x9,8) + ( ½ x 500 x v B 2 ) 3. Conclusion V B = 15,34 m s -1 Activity to Reinforce lesson(educator may summarise the main aspects of the lesson).[5 min.] HOMEWORK QUESTIONS/ ACTIVITY (educator must give learners a few questions to answer at home by either writing them on the chalkboard or giving an exercise from the prescribed textbook) [30 min] RESOURCES USED: worksheets, textbooks Name of Teacher: Sign: Date: HOD: Sign: Date: Page 6

32 GRADE 10 SUBJECT Physical Sciences WEEK 35 Lesson 3 TOPIC Conservation of Mechanical energy- Practical demonstration LESSON SUMMARY FOR: DATE STARTED: DATE COMPLETED: TIME: 60 minutes LESSON OBJECTIVES At the end of the lesson learners should be able to: State the law of conservation of energy State the principle of conservation of mechanical energy Apply law of conservation of mechanical energy in a describing scenarios TEACHING and LEARNING ACTIVITIES 1. TEACHING METHOD/S USED IN THIS LESSON: Demonstration ; observation, question and answer method 2. LESSON DEVELOPMENT 2.1 Introduction a) PRE-KNOWLEDGE learners need understanding of the following: (i) Different form of energy (ii) Potential energy of an object b) BASELINE ASSESSMENT (educator to design a worksheet/ transparency or write questions on the board [preferably a worksheet to save time] to gauge the learners memory of their relevant prior knowledge) QUESTIONS for the BASELINE ASSESSMENT i) List five forms of energy ii) iii) iv) Define potential energy [5 min] Give three examples of potential energy What are the factors that affect the gravitational potential energy of an object Page 1

33 c) Do corrections i) Sound, light, heat, kinetic energy, potential energy etc. ii) Gravitational potential energy is the energy due to object s position or state.(stored energy) iii) Electrical potential energy, gravitational potential energy Nuclear potential energy and Chemical potential energy iv) Mass and the height of an object 2.2 Main Body (Lesson presentation) [30 min] Adapted from Grade 10 Physical Sciences -Siyavula Materials A length of plastic pipe with diameter approximately 20 mm, a marble, some masking tape and a measuring tape. Activity 1 Instructions 1 Questions First put one end of the pipe on the table top so that it is parallel to the top of the table and tape it in position with the masking tape. Lift the other end of the pipe upwards and hold it at a steady height not too high above the table. Measure the vertical height from the table top to the top opening of the pipe. Now put the marble at the top of the pipe and let it go so that it travels through the pipe and out the other end. 1. What is the velocity (i.e. fast, slow, not moving) of the marble when you first put it into the top of the pipe and what does this mean for its gravitational potential and kinetic energy? 2. What is the velocity (i.e. fast, slow, not moving) of the marble when it reaches the other end of the pipe and rolls onto the desk? What does this mean for its gravitational potential and kinetic energy? Activity 2 Instructions 2 Now lift the top of the pipe as high as it will go. Measure the vertical height of the top of the pipe above the table top. Put the marble into the top opening and let it roll through the pipe onto the table. Page 2

34 Questions 3 What is the velocity (i.e. fast, slow, not moving) of the marble when you put it into the top of the pipe, and what does this mean for its gravitational potential and kinetic energy? 4 Compared to the first attempt, what was different about the height of the top of the tube? How do you think this affects the gravitational potential energy of the marble? 5 Compared to your first attempt, was the marble moving faster or slower when it came out of the bottom of the pipe the second time? What does this mean for the kinetic energy of the marble? POSSIBLE OBSERVATIONS The activity with the marble rolling down the pipe shows very nicely the conversion between gravitational potential energy and kinetic energy. In the first instance, the pipe was held relatively low and therefore the gravitational potential energy was also relatively low. The kinetic energy at this point was zero since the marble wasn't moving yet. When the marble rolled out of the other end of the pipe, it was moving relatively slowly, and therefore its kinetic energy was also relatively low. At this point its gravitational potential energy was zero since it was at zero height above the table top. In the second instance, the marble started off higher up and therefore its gravitational potential energy was higher. By the time it got to the bottom of the pipe, its gravitational potential energy was zero (zero height above the table) but its kinetic energy was high since it was moving much faster than the first time. Therefore, the gravitational potential energy was converted completely to kinetic energy (if we ignore friction with the pipe). In the case of the pipe being held higher, the gravitational potential energy at the start was higher, and the kinetic energy (and velocity) of the marble was higher at the end. In other words, the total mechanical energy was higher and only depended on the height you held the pipe above the table top and not on the distance the marble had to travel through the pipe. Corrections [7 min] Possible answers to questions in the activity 1. The pipe was held relatively low and therefore the gravitational potential energy was also relatively low. The kinetic energy at this point was zero since the marble wasn't moving yet. 2. When the marble rolled out of the other end of the pipe, it was moving relatively slowly, and therefore its kinetic energy was also relatively low. At this point its gravitational potential energy was zero since it was at zero height above the table top. 3. The marble started off higher up and therefore its gravitational potential energy was higher. But its velocity at this point is zero, therefore the kinetic energy is also zero 4. On the second attempt, the height is increased. Since the gravitational potential energy depends on the height the object was raised to, the gravitational potential energy is higher where the height is high. 5. The marble was moving faster. All the gravitational potential energy was transferred to kinetic energy. 6. Page 3

35 3. Conclusion Activity to Reinforce lesson(educator may summarise the main aspects of the lesson).[5 min.] HOMEWORK QUESTIONS/ ACTIVITY (educator must give learners a few questions to answer at home by either writing them on the chalkboard or giving an exercise from the prescribed textbook) [30 min] RESOURCES USED: worksheets, textbooks, A length of plastic pipe with diameter approximately 20 mm, a marble, some masking tape and a measuring tape Reflection/notes Name of Teacher: Sign: Date: HOD: Sign: Date: Page 4

36 GRADE 10 SUBJECT Physical Sciences WEEK 35 Lesson 4&5 TOPIC Application of Principle of Mechanical energy (Calculations) LESSON SUMMARY FOR: DATE STARTED: DATE COMPLETED: TIME: 60 minutes LESSON OBJECTIVES At the end of the lesson learners should be able to: Calculate from the equation Ek1 + Ep1 = Ek2 + Ep2. TEACHING and LEARNING ACTIVITIES 1. TEACHING METHOD/S USED IN THIS LESSON: Induction method, question and answer method 2. LESSON DEVELOPMENT 2.1 Introduction a) PRE-KNOWLEDGE learners need understanding of the following: (i) Mechanical energy (ii) Conservation of mechanical energy b) BASELINE ASSESSMENT (educator to design a worksheet/ transparency or write questions on the board [preferably a worksheet to save time] to gauge the learners memory of their relevant prior knowledge) QUESTIONS for the BASELINE ASSESSMENT i) Define mechanical energy ii) iii) iv) [5 min] State conservation of mechanical energy What will happen to mechanical energy if the system is open? Write down the equation used in conservation of mechanical energy. Page 1

37 c) Do corrections i) Mechanical energy is the sum of object s gravitational potential energy and the kinetic energy ii) Mechanical energy (the sum of kinetic energy and the gravitational energy) of a closed system remains the same(constant) iii) Some energy will be converted into sound, heat or light. e.t.c. iv) Ek1 + Ep1 = Ek2 + Ep Main Body (Lesson presentation) [30 min] Mechanical energy is the sum of the gravitational potential energy and the kinetic energy of a system. In a closed system,the sum of kinetic energy and the potential energy remains constant at any point.mathematically it can be written as: Ek1 + Ep1 = Ek2 + Ep2. The total mechanical energy of Li Ping Phar is the sum of the potential and kinetic energies. The two forms of energy sum up to Joules Since the mechanical energy remains constant, the sum of gravitational potential energy and the kinetic energy at any stage in a closed system must be equal. Otherwise the system is an open system. Page 2

38 In an open system some energy is converted into other forms of energy like sound, heat etc. Learners activities 10 min A 2 kg metal ball is suspended from a rope as a pendulum. If it is released from point A and swings down to the point B (the bottom of its arc): Drop a 50 kg rock off a vertical cliff that is 45,92 m high. Calculate its speed when 25, 51 m above the ground A ball of mass 600 g is rolled a distance of 3 meters and it takes 1.5 seconds. What is the kinetic energy of the rolling ball? Average speed = dis tan ce time = 3,0 1,5 = 2 m s -1 and m = 0,6 kg If a mouse and an elephant both run with the same kinetic energy, can you say which is running faster? Explain in terms of the equation for EK State the law of conservation of mechanical energy Page 3

39 Corrections Consider top to be A, and the other point will be B (E P + E K) at A = E P + E K) at B (mgh + 0 )at A = (mgh + ½ m v 2 ) at B 9, 8 x 45, 92 = 9, 8 x 25, 51 + ½ v 2 v 2 = 400 v = 20 m.s See hint on the question itself. EK = ½ mv 2 = ½ (0,6)(2) 2 = 1.2 J Kinetic energy depends on mass and velocity of an object. If the elephant must have the same kinetic energy as the rat, elephant should be running very slow and the rat must run very fast. The kinetic energy is directly proportional to the mass. As the mass increases, so does the kinetic energy. Ek α m b) The kinetic energy is directly proportional to the square of the velocity, i.e. Ek α v 2 Page 4

40 2.2.5 The sum of gravitational potential energy and the kinetic energy in a closed system remains the. 3. Conclusion Activity to Reinforce lesson(educator may summarise the main aspects of the lesson).[5 min.] HOMEWORK QUESTIONS/ ACTIVITY (educator must give learners a few questions to answer at home by either writing them on the chalkboard or giving an exercise from the prescribed textbook) [30 min] RESOURCES USED: worksheets, textbooks Reflection/notes Name of Teacher: Sign: Date: HOD: Sign: Date: Page 5

41 GRADE 10 SUBJECT Physical Sciences WEEK 36 lesson 1 TOPIC The hydrosphere Interaction with other earth systems LESSON SUMMARY FOR: DATE STARTED: DATE COMPLETED: TIME: 60 MIN LESSON OBJECTIVES At the end of the lesson learners should be able to: Identify the hydrosphere Give an overview of its interaction with the atmosphere, lithosphere and biosphere. TEACHING and LEARNING ACTIVITIES 1. TEACHING METHOD/S USED IN THIS LESSON: ; Question and answer, Explanation 2. LESSON DEVELOPMENT 2.1. Introduction [5 min] Discuss the fact that the earth that we live on is the only planet that is known to support life. The temperature of the earth, as well as the gases that are found on the earth, is suitable for life to survive. PRE-KNOWLEDGE A basic understanding of the following: The lithosphere (or geosphere consists of all the rock formations that forms the earth s crust. The atmosphere consists of the air that surrounds the earth. The biosphere - consists of all the living organisms that are found on earth Main Body (Lesson presentation) [30 min] The hydrosphere, also called the water sphere, consists of all the earth s water. Water is the most common substance on the earth s surface it comprises more than 70% of the surface. The Blue Earth is sometimes called the Blue Planet because most of it is covered with water. Page 1

42 The hydrosphere includes: All the water on, near or under the earth s surface. It exists as liquid water in the sea, lakes, rivers and ground water. Water also exists as solid ice in the frozen polar ice caps, in glaziers and icebergs and frozen soil layers as permafrost. Water vapour in the atmosphere. Water moves through the global systems and influences all of them. Movement of water of oceans and on the surface of land is controlled by energy from the sun. These interactions are sometimes known as the water cycle. The water cycle consists of : Evaporation, transpiration, condensation and precipitation, infiltration, surface run-off. Interaction of hydrosphere with the atmosphere. When water is heated, it evaporates and forms water vapour. The vapour cools again, condenses to form liquid water that returns to the surface by precipitation (snow, rain, hail or sleet.) As the cycle of water moves through the atmosphere it drives weather patterns on the earth. Page 2

43 Interaction of the hydrosphere with the lithosphere. Water is responsible for erosion. It causes weathering and transportation of fragments of rocks. Erosion helps to shape the surface of the earth. River valleys in mountains have been carved out by the action of water. Cliffs and caves on rocky beach coastlines are also the result of weathering. Weather increases the amount of dissolved minerals in rivers etc. This is important for plants and animals that live in the water. Interaction of the hydrosphere and the biosphere. Water is essential for life on earth. Plants absorb water through their roots and transport it to their leaves, Water is then returned back to the atmosphere. Animals release water vapour into the atmosphere as they breathe. Water is also stored in the bodies of animals to transport food. Water is excreted to cool animals down. LEARNER ACTIVITY [15 min] CLASSWORK ACTIVITY: Answer the following questions 1. Explain how it is possible that all three phases of water can be present in the lithosphere. 2. Identify the different earth systems in the following diagram: Page 3

44 3. Water changes as it goes through the water cycle Is phase change a physical or a chemical change? 3.2. Give one example in the water cycle of each of the following phase changes Liquid to gas Gas to liquid Liquid to solid 4. The diagram below represents the water cycle. Choose the correct process from the table below to match the given numbers in the diagram. evaporation; surface runoff; condensation; precipitation; respiration; transpiration; infiltration Page 4

45 ANSWERS for the CLASSWORK ACTIVITY 1. Water exists in the following forms: In the gas phase in the crust of the earth. In the liquid phase as groundwater. As part of crystals in certain minerals 2. Air: Atmosphere Land: Lithosphere Water: Hydrosphere Living organisms: Biosphere A physical change Evaporation of sea water Condensation to form clouds Formation of hail Evaporation 4.5 Precipitation 4.2 Transpiration 4.6 Infiltration 4.3 Respiration 4.7 Surface runoff 4.4 Condensation Page 5

46 3. Conclusion [10 min] Educator discusses the answers of the classwork activity. HOMEWORK QUESTIONS/ ACTIVITY Educator asks learners to do one or more of the following: find pictures or draw diagrams to illustrate the importance of water on Earth; write a short passage to discuss the importance of the hydrosphere on earth. Recourses: Diagrams and photos to explain the different concepts, power point presentation, transparency; prescribed text books, CAPSdocument (page 60,61). Name of Teacher: Sign: Date: HOD: Sign: Date: Page 6

47 GRADE 10 SUBJECT Physical Sciences WEEK 36 lesson 2 TOPIC The hydrosphere - Tie importance of the hydrosphere LESSON SUMMARY FOR: DATE STARTED: DATE COMPLETED: TIME: 60 MIN LESSON OBJECTIVES At the end of the lesson learners should be able to: Understand the importance of the hydrosphere. Discuss factors that threaten the water supplies on Earth. Understand Water reservoirs on Earth. Understand problems with water supply in South Africa TEACHING and LEARNING ACTIVITIES 1. TEACHING METHOD/S USED IN THIS LESSON: ; Class discussion, Question and answer, Explanation, 2. LESSON DEVELOPMENT 2.1. Introduction [10 min] Allow learners to discuss their views on the importance of the hydrosphere Main Body (Lesson presentation) [30 min] There are four main reasons why water is important. Water is part of living cells: Each cell in a living organism is made up of almost 75% water. This allows the cell to function normally. Most of the chemical reactions that occur in life, involve substances that are dissolved in water. Water provides a habitat: Many animals and plants live in the hydrosphere. Gases (e.g. CO2 and O2), nutrients (e.g. nitrates (NO3 = ), nitrites (NO2 = ), ammonium (NH4 + )) and different other ions (e.g. Mg 2+ and Ca 2+ ) are dissolved in water. Page 1

48 The substances mentioned above are critical for life to exist in water. Regulating the climate: Water has a high specific heat. It means that water takes a long time to heat up and also a long time to cool down. This significant characteristic of water is important in helping to regulate temperatures on earth so that they stay within a range that is acceptable for life to exist. Ocean currents also disperse heat. Human needs: Water is used to generate electricity. Drinking water is important. Water is used for washing and cleaning. Water is used in different industrial processes. Factors that threaten the hydrosphere: Pollution: Animals and plants that live on the Earth s water bodies are specially adapted to surviving within a certain range of conditions. If these conditions are changed, these organisms may not survive. Pollution can affect entire ecosystems. The most common forms of pollution in the hydrosphere are waste products from humans and industries, fertiliser runoff that causes eutrophication (excessive plant growth) and toxic trace elements like aluminium, mercury, lead and copper. Most of these elements come from mines or industries Overuse of water: It is impossible to imagine a day without water! Only a small percentage of the hydrosphere s water is available as fresh water. Humans use so much water, that a point is almost reached where the consumption is approaching the amount o f water that is available. Since South Africa is a dry country, it is estimated that between 2020 and 2040, water supplies will no longer be able to meet the growing demand for water in the country. Page 2

49 LEARNER ACTIVITY [15 min] GROUP DISCUSSION: Creative water conservation Educator can use the guidelines on page 467 of Physical Science (grade 10) Siyavula, to introduce the important topic of water conservation. 3. Conclusion [5 min] Educator summarises the learner s views on conservation of water. HOMEWORK QUESTIONS/ ACTIVITY [10 min] Answer the following questions at home: 1. What is South Africa s policy about water? 2. Discuss methods that communities can follow to keep the water that they use clean? 3. The Tsunami in Japan caused great damage to all the different spheres of the Earth. Page 3

50 Discuss the interaction of this event with the different spheres: Event Hydrosphere Hydrosphere Lithosphere Hydrosphere Biosphere Recourses: Internet websites, power point presentation, transparency; prescribed text books, CAPS-document (page 60,61). Name of Teacher: Sign: Date: HOD: Sign: Date: Page 4

51 GRADE 10 SUBJECT Physical Sciences WEEK 36 lesson 3 TOPIC The hydrosphere Water reservoirs and supply in South Africa LESSON SUMMARY FOR: DATE STARTED: DATE COMPLETED: TIME: 60 MIN LESSON OBJECTIVES At the end of the lesson learners should be able to: Identify water reservoirs on Earth. Understand water supply in South Africa. Study the ecology of rivers in South Africa. TEACHING and LEARNING ACTIVITIES 1. TEACHING METHOD/S USED IN THIS LESSON: ; Question and answer, Explanation 2. LESSON DEVELOPMENT 2.1 Introduction [5 min] Educator discusses homework questions with learners. Answers: 1. According to South Africa s Constitution, each person has the right to live in a healthy environment. Therefore they have the right to clean drinking water. The Government and Local Authorities have the responsibility to provide clean water to citizens Filtrate water through a clean cloth or sand. Boil afterwards. After filtrating and boiling a few drops of lemon juice or chlorine (Jik) can be added. 3.1 The earthquake (event) triggered powerful tsunami waves (hydrosphere). 3.2 The huge waves reached the land. Buildings were flooded; structures were broken down and more earthquakes followed. 3.3 Vegetation and agricultural land were destroyed. People and animals were killed, Water was polluted and famine followed Page 1

52 PRE-KNOWLEDGE A basic understanding of the following: The characteristics of water. 2.2 Main Body (Lesson presentation) [30 min] Most of the water on the earth exists in the liquid phase. Different sources of water are: 97% in the oceans 1,8 % in glaziers and ice peaks (),9% is groundwater 0,02% is surface water in lakes, seas and inland rivers 0,001% is atmospheric water vapour at any given moment Liquid water is found in various masses on earth e.g. oceans, seas, lakes, rivers, streams, canals and pools, Largest amount of water on earth is ocean water. Water is also present in the atmosphere in the liquid and vapour phase. It also exists as groundwater in underground sources. Water is found in the solid phase as ice in the polar ice caps. The normal boiling point of water is C, but in deep sea geysers it can superheat at C. Where the atmospheric pressure is low e.g. on Mount Everest, water boils at about 70 0 C. South Africa is a very dry country and rain mostly fall in a small belt along the eastern and southern coastlines. We rely on rivers, dams and underground water for our water supply. The ecology of rivers. The downwards flow of rivers from mountainous highlands takes place in three Phases: Page 2

53 The interaction of the biological community of organisms with the environment is different in each phase. The three phases form a river system with a range of ecosystems. Phase 1 Mountain streams with cold, clear water accelerates downwards. Phase 2 Streams flow together to form wider and deeper streams. Page 3

54 Phase 3 Deeper rivers meander. Bloukrans River At the mouth of the river it can be divided into several channels to form a delta or wetland. The ecology of life in a river depends on seasonal rainfall and flooding. Insects and fish also depends on flooding for food and reproduction, Riverbanks and flood planes are enriched by the flooding. Water, plants and animals, that forms an ecosystem, are always interdependent of each other. Page 4

55 LEARNER ACTIVITY [20 min] PRACTICAL ACTIVITY: Study the ecology of a river in your area 3 Conclusion [5 min] Educator divides learners into small groups. Each group has to identify a river (obtain a map or visit the river). Find out about the flooding of the river: Talk to people that live along the riverside. Do research about the history of the flooding of the river. Establish a pattern of flooding. Find out about the plants and animals that live in the river. Write a report about the ecology of the river. Educator summarises the concept of river ecology and allow learners to ask questions about their study. HOMEWORK QUESTIONS/ ACTIVITY Learners complete their study of the ecology of the river of their choice. Recourses: Diagrams and photos to explain river ecology, power point presentation, transparency; prescribed text books, CAPS-document (page 60,61). Name of Teacher: Sign: Date: HOD: Sign: Date: Page 5

56 GRADE 10 SUBJECT Physical Sciences WEEK 36 lesson 4 TOPIC The hydrosphere Advantages and disadvantages of dams on the lives of people and the ecology in the region LESSON SUMMARY FOR: DATE STARTED: DATE COMPLETED: TIME : 60 MIN At the end of the lesson learners should be able to: Discuss the importance of building dams. Discuss the advantages of a dam on the environment. Discuss the disadvantages of a dam on the environment. 1. TEACHING METHOD/S USED IN THIS LESSON: Question and answer, Explanation 2. LESSON DEVELOPMENT 2.1. Introduction [10 min] TEACHING and LEARNING ACTIVITIES Educator allows learners to ask questions and discuss their study on river ecology. Educator discusses the fact that South Africa is a dry country There are very few lakes in the country and we have to rely on rivers, dams and ground water for water supply. PRE-KNOWLEDGE A basic understanding of the following: Ecology of rivers and the interdependence of the different role-players in the ecosystem of rivers Main Body (Lesson presentation) [30 min] Dams are built as a way to increase the water supply in a specific area. A dam is a barrier that controls the flow of water in a river. A huge water surface is created and the flow of water from the dam is controlled by opening or closing sluices. South Africa is one of the 30 driest countries in the world. To make sure that we have enough water to drink, to grow food and for industries, the government builds dams to store water. Page 1

57 These dams make sure that communities do not run out of water in times of drought. About half of South Africa s annual rainfall is stored in dams. Dams can also prevent flooding when there is an overabundance of water. We have more than 500 government dams in South Africa, with a total capacity of million cubic metres (about 15-million Olympic-sized swimming pools). The Biggest Dam in South Africa is the Gariep Dam, which is situated in the Orange River. Gariep dam Orange River Advantages of a dam on environment and people Stores drinking water for humans and animals. Provides water for domestic needs. Provides water for industries in the area. Provides recreation facilities like fishing, camping, rowing etc. Can generate hydro-electricity. Can control floods that damages crops and buildings. The Kariba Hydro-electric Dam in the Zambezi River Page 2

58 Disadvantages of a dam on environment and people Damming of water prevents natural flooding of water in a river. Silt on the banks of the river is not washed back into the river and correct feeding and habitat for plants and animal life is no longer provided. Big dams have a negative impact on plant- and aquatic life ecosystems. Evaporation from the large surface of the dam causes water waste. Evaporation is a cooling process. This results in layers of water with different temperatures and cold water without air can be trapped at the bottom of the dam. Water without oxygen can kill the aquatic life at the bottom of the river. Materials like sand, clay or pieces of rock can be carried into the dam by water or wind. These sediments can flow into the river and clog it. People that rely on fishing to make ends meat, suffers because the fish population in the dam often decreases. People that lived above the dam wall have to be relocated because the original valley is flooded. When the sluices are opened, large amounts of water is released. Animals and insects that live in that area are influenced negatively. Human impact on water It is very important that learners should understand their responsibility for water supplies in our country. Human activity has a huge impact on the supply and quality of water. The natural water reservoirs are contaminated by human negligence and this is threatening the quality of our water supplies. Informal settlements: People use rivers and streams for washing and bathing. Agriculture: Domestic animals grazing on river banks contaminate the water. Farmers allow pesticides and fertilizers to flow in rivers, causing eutrophication of the water. Wetland destruction: Large quantities of rainwater are stored in these areas and they must be preserved. Forestry: Exotic trees, used for commercial purposes use a lot of water. Littering: Plastic bags and other rubbish pollute rivers. Medicine, chemicals and oils: These substances are poured into drains by domestic households and industries and they pollute the water. Power stations: Can cause thermal pollution: Page 3

59 LEARNER ACTIVITY [15 min] CLASSWORK ACTIVITY: Answer the following questions. Dams are built for different reasons. We can distinguish between earth-fill dams, storage dams, diversion dams and hydro- electric dams. Explain the use of each of the above-mentioned dams. 1. It is known that a dam in the area of your school contains sulphates. The grade 10 Physical Sciences class has been asked to conduct a research project to determine the percentage of sulphates present in the dam. The test has to be conducted over a period of four weeks. Water has to be collected from the dam on a Monday at 11H00 at the same place. 30 ml of water must be collected at a depth of 50 cm below the surface of the water. The learners obtained the following results: Ions in sample Volume of sample Day 1 Day 2 Day 3 Day 4 %Sulphates 30 ml 1,5 2,5 3,7 5.5 Answer the following questions: 2.1 Identify the independent variable. 2.2 Name the dependent variable(s). 2.3 Which variable(s) have been controlled? 2.4 Which apparatus have been needed to complete the experiment? 2.5 The learners used specific chemical solutions to conduct the test. Give the name and formula of the substances. 2.6 The test is based on the formation of a precipitate. Explain the meaning of the word precipitate. 2.7 Discuss the test and provide an appropriate net ionic reaction. 2.8 Draw a line graph of the results obtained in the test. 2.9 Write a conclusion for this investigation. Page 4

60 %sulphates Grade 10 Physical Science Lesson Plans ANSWERS for the CLASSWORK ACTIVITY 1. Earth-fill dams: built in rivers and streamlets used for irrigation. Storage dams: used to store and provide water to the community. Diversion dams: prevents flooding in small areas. Hydro-electric dams: built with high concrete walls and used to generate electricity Days/time 2.2 Percentage of sulphates 2.3 The same volume of water is used; samples are collected on the same day and at the same time; the depth of the water is the same. 2.4 Water samples; watch; measuring stick; test tubes and stoppers; test tube holder; 2.5 Barium chloride solution (BaCl2(aq); concentrated nitric acid HNO3(l) 2.6 A precipitate is an insoluble solid in water. 2.7 A precipitate is formed if sulphate ions are present. The precipitate is insoluble in concentrated nitric acid. Ba 2+ (aq) + SO4 2= (aq) BaSO4(s) 2.8 Graph of %sulphates against days Days 2.9 The %sulphates have increased over a period of 4 weeks. The straight line graph indicates a direct proportionality. Page 5

61 Conclusion [5 min] Educator discusses the answers of the classwork activity. Educator summarises important aspects of the lesson, reinforcing what needs to be remembered and recalled. HOMEWORK QUESTIONS/ ACTIVITY Educator instructs learners to find articles in news papers, magazines or the internet (if they have access) that covers any aspect of water purification, dams (advantages and disadvantages) and conservation of water. Resources: Power point presentation, transparency; prescribed text books, Doc Scientia, Internet. Name of Teacher: Sign: Date: HOD: Sign: Date: Page 6

62 GRADE 10 SUBJECT Physical Sciences WEEK 37 lesson 1&2 TOPIC The hydrosphere Purification of water LESSON SUMMARY FOR: DATE STARTED: DATE COMPLETED: LESSON OBJECTIVES At the end of the lesson learners should be able to: Attempt the project for formal assessment. TEACHING and LEARNING ACTIVITIES 1. TEACHING METHOD/S USED IN THIS LESSON: ; Explanation and discussion 2. LESSON DEVELOPMENT 2.1. Introduction [10 min] 2.2 Main body [40 min] Educator briefly discusses the need for clean water in South Africa. It is important that learners realise that they can also contribute to promoting water conservation. Educator uses the lesson to explain to learners what is expected from them. CLASSWORK ACTIVITY: Designing a poster Educator announces the topic for formal assessment: South Africans have to become Water Wise. (Note that "Water Wise" is Rand Water's environmental brand. It is a campaign aimed at increasing awareness of the need to value water and to use it wisely. South Africa is a water stressed country, and the water resources are under tremendous pressure from a growing population, on going development, pollution, wetland destruction, alien invasive plants and the effects of global warming.) Water is freely available from the natural water cycle but due to water in South Africa being a scarce resource and often a polluted resource, many systems need to be put into place so that we receive enough clean healthy water, i.e. dams, water transfer schemes, water purification stations, reservoirs, pipelines, etc. These systems cost large amounts of money and this is why we have to pay for water. At the moment you pay between R4 & R16 for 1000 litres for tap water, which is very cheap compared to your grocery items. If we continue to waste and pollute water then that cost will drastically increase. More dams and water transfer schemes will have to be built, and further technology will have to be included in Rand Water s purification process, or further infrastructure built, to clean polluted water. That is why it is so important for people to change their attitude towards water, treat it with respect and use it wisely. It is important that we all become Water Wise! Page 1

63 To be Water Wise means that a person will: have the utmost RESPECT for water and all life; use water carefully and not WASTE it; not POLLUTE rivers with liquid and solid waste; PAY for water services; take ACTION to solve any water problems; CONSERVE water, and thereby CONSERVE the natural environment. Instructions: Use the information above to complete the following: A. Design a poster with the heading: Water wise. B. Size of poster: A3. Information must be obvious and presented in an interesting manner. (See attached rubric). Discuss the quality of water in South Africa. Refer to aspects like: ph levels of the water The effect of ions present in the water on animals and plants, The causes of cholera and how it can be prevented. Do research on the process of water purification. Explain why purification plants are necessary. Discuss each of the different phases of purification. C. Use pictures and diagrams to enhance the quality of information. D. The literature study must be provided with a cover page, index page and bibliography and can be typed or written. E. Be careful not to plagiarise! (50) (See attached rubric) Assessment Criteria Content: Main points Selected points are irrelevant Some points are relevant All the important main points are included Facts/Concepts Facts are mainly incorrect Some of the facts are incorrect Facts are correct All the main facts are correct and concepts are clear and expressed in a Page 2

64 logical way Presentation: Size of poster (A3) Incorrect size Correct size Font size Too small, font not appropriate Too small, but clear font chosen Organisation/layout Muddled Some organisation is evident Some large enough, font is clear Organisation is clear and logical Font is clear and large enough to read from 1 m Organisation is clear and logical, well designed Use of colour Only one colour is used Colours are used, but the effect is not good Good colour usage Contrasting colours used-effect is interesting Public appeal Not appealing May appeal to some, but room for improvement Appealing to most Eye-catching very interesting Personal information Not included Some included Included TOTAL 45/5 (Convert to 9) Criteria Marks Commentary Presentation: Content, headings, Sub headings Neatness Untidy, very little headings and sub headings Good presentation, although a better choice of headings could explain certain aspects better Excellent presentation, headings are descriptive and contribute to meaning of content (x2) Page 3

65 Graphics: Illustrations, diagrams, graphs No graphics graphics are untidy and not relevant Graphics are neat, but did not always complement the content Choice of graphics is excellent and explains the content. Creative and effective use of colour (x3) Introduction: explain the aim of the research No introduction Introduction given, but it is not relevant State the aim of the project and rouse the interest of the reader Content Very little is said about the topic Discusses only certain aspects of the given topic Do some research on the quality of water and water purification, but do not refer to the impact on human development and environment (x3) Excellent research is done evaluate the impact on human development, the environment and sustainable development (x5) Conclusion correct and Conclusion No conclusion Attempt, but incorrect Conclusion is given, but not based on the research (x2) logical, explanation supported by research (x3) Poster Mark with rubric for poster Bibliography No resources mentioned Resources are mentioned, but not referred to in research Adequate recourses mentioned and referred to in research Page 4

66 Total mark for formal assessment is [50] 3. Conclusion [10 min] Educator ensures that all the learners have the right understanding of the formal assessment HOMEWORK QUESTIONS/ ACTIVITY Learners do research for the project. Recourses: Transparency; prescribed text books, web sites e.g. Study and Master Physical Sciences Grade 10 (Rubrics) CAPSdocument (page 60, 61). Name of Teacher: Sign: Date: HOD: Sign: Date: Page 5

67 GRADE 10 SUBJECT Physical Sciences WEEK 37 lesson 3 TOPIC The hydrosphere Purification of water LESSON SUMMARY FOR: DATE STARTED: LESSON OBJECTIVES DATE COMPLETED: At the end of the lesson learners should be able to: Discuss the steps hat are involved in the purification of water to obtain clean drinking water. Draw a flow diagram and explain the different purification processes. 1. TEACHING METHOD/S USED IN THIS LESSON: ; Question and answer, Explanation, Practical activity (experiment) 2. LESSON DEVELOPMENT 2.1. Introduction [5 min] TEACHING and LEARNING ACTIVITIES Educator explains the fact that water from rivers and dams are never clean enough for human consumption. The water contains bacteria, ions from the ground and gases from the air. It can also be contaminated by mud, sand, leaves, twigs and debris. Water has to go through a process of purification, See for interesting information PRE-KNOWLEDGE A basic understanding of the following: The meaning of the terms filtration and disinfection. The process of dissociation Precipitation reactions Main Body (Lesson presentation) [20 min] Rand Water draws water for purification from the Vaal Dam. This water is transported via canals and pipelines to Rand Water s two purification stations in Vereeniging. Here the water is cleaned and treated to a standard suitable for humans to drink. Page 1

68 The water complies with the requirements of the South African National Standard for Drinking Water (SANS 241) and the World Health Organisation (WHO) guidelines. The purified drinking water is pumped in underground pipelines from the purification stations, via a series of pump stations, stored in closed reservoirs and then distributed via underground pipes, using the force of gravity. Rand Water sells water to local authorities, and some mines and factories, in an area of square kilometres. The local authorities then supply 11 million people in homes, schools, and businesses in Gauteng and parts of Mpumalanga, North West, Free State and Limpopo Provinces with clean water they buy from Rand Water. This accounts for 45% of the South African population and 60% of the economy. Water purification involves four important steps: Page 2

69 Flocculation Small suspended particles in the water join together to form larger, heavier particles. These particles sink to the bottom. Flocculation is achieved by adding aluminium sulphate (alum) and calcium hydroxide (lime) to the water. Lime dissolves (dissociates) in water: Ca(OH)2(s) Ca 2+ (aq) + 2OH - (aq) The Ca(OH)2 is added to neutralise acids and also provides hydroxide ions in the water supply. Al2(SO4)3(s) Al 3+ (aq) + 3SO4 2- (aq) Al 3+ (aq) +3OH - (aq) Al(OH)3(s) This jelly-like precipitate, called the flock, traps other particles and removes colour and other micro organisms from the water. Settling The water now exits the flocculation basin and enters the sedimentation basin. The flow of water is slow in this tank, allowing the flock to settle. A layer of sludge is formed on the floor. Flocculation Sludge deposit Filtering Water from the sedimentation basin is allowed to drain through large filters. The filters remove objects like logs, plastic bags and other floating debris. Disinfection Disinfection is done by adding chlorine to the water. Chlorine reacts with the water to form a molecule called hypochlorite. (HOCl). The HOCl-molecules diffuse through the cell walls of micro-organisms and destroy their ability to function. After chlorination the water is considered to be safe for human consumption. Filtering of water A water purification plant Page 3

70 LEARNER ACTIVITY [30 min] It is important to realise that the hydrosphere exists in a delicate balance with other systems and that disturbing the balance can have serious consequences for life on this planet (Abstract taken from Physical Science Grade 10 p468 Siyavula) Educator divides learners in groups. They have to discuss actions that can be taken by the class to make people and other learners in the school, more aware of how important it is to conserve water. Discussions can be in the form of a debate. Learners have to come up with a list of suggestions at the end of the discussion. 3. Conclusion [5] Educator summarises learner s views on water conservation. It is important that learners must be made aware of the importance of this topic. They have to understand that it is the duty of each person to save as much water as possible. HOMEWORK QUESTIONS/ ACTIVITY Learners have to prepare for a revision test on the interaction between the different spheres of the Earth, rivers, dams and water purification. Recourses: Diagrams and photos to explain the different concepts, power point presentation, web sites e.g. and transparency; prescribed text books, CAPS-document (page 60,61). Name of Teacher: Sign: Date: HOD: Sign: Date: Page 4

71 GRADE 10 SUBJECT Physical Sciences WEEK 37 lesson 3 TOPIC The hydrosphere Purification of water LESSON SUMMARY FOR: DATE STARTED: DATE COMPLETED: TIME: 60 MIN LESSON OBJECTIVES At the end of the lesson learners should: Understand the importance of clean drinking water Understand the meaning and influence of the ph of water on water quality. Be able to identify ions that might be present in water samples. TEACHING and LEARNING ACTIVITIES 1. TEACHING METHOD/S USED IN THIS LESSON: Revision test, Question and answer, Explanation, 2. LESSON DEVELOPMENT 2.1. Introduction [20 min] Questions Learners write the revision test. Method of assessment: Peer assessment. 1. Multiple choice questions 1.1 The bonds between water molecules in ice is: a. covalent bonds b. Van der Waals forces c. Hydrogen bonds d. Water bonds 1.2 Water in all three phases is known as the a. Atmosphere Page 1

72 b. Hydrosphere c. Lithosphere d. Biosphere 1.3 It substance that is insoluble in water, is called a; a. Crystal lattice b. Macro molecular structure c. Solute d. Precipitate 1.4 The following is not a greenhouse gas: a. Water vapour b. Nitrogen c. Ozone d. Carbon dioxide (4 x 2 = 8) Contextual question 2. Some of the gases in the atmosphere dissolve in water vapour to form acid rain. Write balanced equations to represent the following dissolution processes and give the name of the product that is formed Carbon dioxide in water 2.2. Sulphur dioxide in water (6) 3. Give the definition of each of the following: 3.1. Condensation 3.2. Transpiration 3.3. Precipitation (6) 4. Give three reasons why building dams can impact negatively on people and the environment. (3) 5. Name three positive effects of the building of dams on people and the environment. (3) 6. Name the four sphere of the earth that is in constant interaction with each other. (4) Page 2

73 [30] Answers c 1.2. b 1.3. d 1.4. b (8) CO2(g) + H2O(g) H2CO3(aq) Carbonic acid 2.2. SO2(g) + H2O(g) H2SO3(aq) Sulphurous acid (6) The phase change where a gas changes into a liquid Water is released from the leaves of plants Water returns to earth in the form of rain, hail, snow or dew. (6) 4. Any three applicable negative impacts can be marked. (3) 5. Any three positive impacts can be marked. (3) 6. Hydrosphere, lithosphere, atmosphere, biosphere. (4) [30] PRE-KNOWLEDGE A basic understanding of the following: Characteristics of water. Reactions of water. Page 3

74 2.2. Main Body (Lesson presentation) [30 min] Educator revises the geometry (shape) of the water molecule. Due to its angular shape, the molecule is polar, which explains the fact that ionic and polar substances can be dissolved in the water. When you drink a glass of water you are not just drinking water, but also other substances that are dissolved in the water. Some of these substances come from the purification process, while others come from the environment. Water pollution increases the amount of impurities to an extent that it is unsafe for drinking. Ions like Na +, Cl =, Ca 2+, Mg 2+, CO3 2-, NO3 - and NO2 - are safe for humans to consume in small amounts. It is only if these amounts rise above safe levels, that water can be considered as polluted. The presence of ions in water samples can be observed by doing simple chemical reactions e.g. precipitation reactions. There are also test kits available that can be used to perform some of these tests. The ph of the water is also important (ph refers to the degree of acidity of the water). If the ph is greater than 7, the water is too basic and can cause problems when consumed by humans. Water with a ph that is too high or to low, can also irritate the eyes of people that are swimming in the water. The ph of the water depends on ions that are dissolved in the water. ph varies between 0 and 14. If the ph is between 0 and 7, the substance is acidic and if it is between 7 and 14, the substance is basic. The diagram below indicates the ph of a few household substances. Page 4

75 Indicators can be used to determine the ph of a solution. Colours of different indicators Indicator paper strips Page 5

76 The ph of drinking water should be around 7. Rainwater often becomes acidic because gases like SO2 and NO2 and CO2 are dissolved in it. 3. Conclusion [10 min] Educator explains the purpose of the practical activity that will be performed in the next lesson. Learners have to bring five different water samples to the classroom, e.g. tap water, water from a river, dam, borehole etc. They have to perform tests to determine The ph of the sample The presence of carbonates, sulphates, chlorides, nitrites and nitrates in the sample. HOMEWORK QUESTIONS/ ACTIVITY Educator motivates learners to complete the project for formal assessment. They have to revise the precipitation reactions of water, done in term 3. Recourses: Diagrams and photos to explain the different concepts, power point presentation, transparency; prescribed text books, CAPS-document (page 60,61). Name of Teacher: Sign: Date: HOD: Sign: Date: Page 6

77 GRADE 10 SUBJECT Physical Sciences WEEK 37 lesson 5&6 TOPIC The hydrosphere Water purity LESSON SUMMARY FOR: DATE STARTED: LESSON OBJECTIVES DATE COMPLETED: At the end of the lesson learners should be able to: Test the ph and purity of different water samples. Test for the presence of carbonates, sulphates, chlorides, nitrates and nitrites. 1. TEACHING METHOD/S USED IN THIS LESSON: ; Question and answer, Explanation, Practical activity (experiment) 2. LESSON DEVELOPMENT 2.1. Introduction [10 min] Educator divides learners in small groups. TEACHING and LEARNING ACTIVITIES Make sure that apparatus and chemicals are available for learners and that they are aware of safety precautions. Educator discusses the procedure of the practical activity. PRE-KNOWLEDGE A basic understanding of the following: Precipitation reactions. The meaning of ph. Handling of chemicals and apparatus. general laboratory rules. 2.2 LEARNER ACTIVITY [45 min] PRACTICAL ACTIVITY (Informal Assessment) Aim: To test the purity and ph of different water samples. Page 1

78 Apparatus: Different water samples e.g. tap water, water from a local dam, river, stream and bore-hole Microscope or magnifying glass Barium chloride solution; silver nitrate solution; concentrated nitric acid Universal indicator strips TETRA strips Enough test tubes Medicine dropper Method Pour the first water sample in each of five test tubes. Use barium chloride to test for nitrates and sulphates. Use concentrated nitric acid to confirm. Use silver nitrate to test for chlorides and confirm with concentrated nitric acid. Use TETRA strips to test for nitrates and nitrites. Use universal indicator strips and determine the ph of the water. Study the water sample under the microscope. Write down your observations and repeat the test with the remaining samples. Observations Summarise the results in a table with appropriate headings. QUESTIONS for the PRACTICAL ATIVITY TETRA strips are used to test for nitrates and nitrites in water Draw diagrams of the particles and microscopic life that is observed under the microscope. Where possible, give a balanced ionic equation for the reaction that takes place. Which of the water samples that were tested can be considered as safe drinking water (Use the test results to answer the question) Discuss the negative effect of each of the following on water. Too high concentrations of carbonates, chlorides, and nitrates in water. Too high or low ph. Page 2